Question

How many atoms of carbon are contained in 47.6 g of Al2(CO3)3? The molar mass of Al2(CO3)3 is 233.99 g/mol.

Answer 1

Molar mass of Al2(CO3)3 = 233.99 g/mol

mass(Al2(CO3)3)= 47.6 g

use:

number of mol of Al2(CO3)3,

n = mass of Al2(CO3)3/molar mass of Al2(CO3)3

=(47.6 g)/(2.34*10^2 g/mol)

= 0.2034 mol

This is number of moles of Al2(CO3)3

one mole of Al2(CO3)3 contains 3 mole of C

use:

number of moles of C = 3 * number of moles of Al2(CO3)3

= 3 * 0.2034

= 0.6103

Number of atoms of C = number of moles of C * Avogadro’s number

= 0.6103 * 6.022*10^23

= 3.68*10^23 atoms

Answer: 3.68*10^23 atoms